Crews are gearing up for the last major challenge of the Nalley Valley traffic project – building an off-ramp that will connect northbound Interstate 5 to state Route 16.
In preparation, the 38th Street on-ramp to both highways was closed on Saturday and will not reopen until the project is complete this summer.
A signed detour is rerouting drivers to 56th Street. Starting in May, drivers bound for westbound state Route 16 off northbound I-5 will be diverted to a temporary roadway that is being constructed.
The shift to a temporary roadway will last six to eight weeks, until the ramp is complete.
“We’re down to the threemonth countdown,” said Lisa Copeland, a spokeswoman with the state Department of Transportation. “This is the last round of big impacts.”
The ramp closure and temporary roadway will allow workers to begin grading and filling the approach to the 1,060-foot-long curved bridge that has been called the highlight of the $184 million project.
The cantilever design is a first for the Transportation Department and was pieced together in mid-air by lifting 112 concrete sections.
The new approach will replace the section that directed northbound vehicles on I-5 heading for state Route 16 into a single lane before merging them with traffic getting off I-5’s southbound lane and continuing to the old Sprague Avenue exit.
While building the new ramp, crews will continue doing bridge-deck and barrier work, as well as a final overlay on the new bridge. After that, striping and traffic signing will begin.
The new westbound viaduct is expected to be complete by June.